Thin Film Surface Coatings for Toughened Dental Ceramics

描述（由申请人提供）：陶瓷是替代金属基修复材料的理想候选材料。陶瓷具有优异的化学耐久性、耐磨性、生物相容性、环境友好性和美观性。然而，全瓷修复体的广泛使用受到了边缘抗折性和临床寿命的影响。这项正在进行的研究的总体目标是开发一种实用的方法，通过用沉积的薄膜表面涂层进行改性来生产更坚固、更耐疲劳的全陶瓷牙科修复体。在资助的6年NIH项目（一次更新）内进行的研究集中在沉积膜的微观结构控制，评估膜对改性陶瓷基板的机械行为的影响，以及影响膜应力和基板行为的膜/环境相互作用的表征。在最初的3年期间，氧化钇稳定的氧化锆（YSZ）被确定为最好的薄膜陶瓷涂层材料的拟议应用。研究表明，YSZ薄膜对与改性牙科陶瓷表面的粘合或半透明陶瓷的美观性不会产生有害影响。在第二个3年期间，沉积的YSZ薄膜和环境水分之间的独特的相互作用进行了鉴定和表征。这些薄膜的TEM分析产生的证据，以及定义和可控的tetraxylonoclinic相变附近的内部缺陷。这些可以被操纵以定制膜应力。韧性/脆性聚合物/YSZ层压薄膜的初步研究表明，有希望提高脆性牙科基材的抗断裂性与控制的YSZ/水蒸气相互作用机制。这些结构的建模表明，可以创建特定的薄膜结构，以在不同的环境中提供最佳效益。这项持续研究的拟议具体目标是：1）检验结合结构和应力状态信息的演变YSZ薄膜的有限元分析（FEA）可以预测纳米和微米尺寸缺陷的集中/分布的假设，2）检验具有交替的延性/脆性的薄膜层压体，低/高模量（聚对二甲苯/YSZ）层将允许精细控制薄膜和膜/基底界面应力，允许方向性的改变。（拉伸、压缩或零）和这些应力的大小，以及薄膜与待再现地控制的局部环境的相互作用，3）测试具有交替的韧性/脆性、低/高模量层的薄膜层压材料将显著增强传统市售牙科陶瓷的耐久性的假设，以及4）证明用于YSZ和聚对二甲苯/YSZ薄膜的不同排列的实际实验室处理的可行技术（实际的台式原型沉积系统的开发）。相信这项研究将对现有的牙科陶瓷技术产生直接的积极影响，扩大低强度材料（如瓷）的潜在应用范围，并提高长期临床疗效。开发非金属（例如，汞齐替代物）修复材料由于与金属废物和处置相关的生物相容性问题和环境问题而成为高度优先的研究。陶瓷提供了生物相容性和环境友好性的最佳组合，但传统上它们的长期临床性能较差。本研究所研究的技术有可能显著提高现有牙科陶瓷的功效，是一种相对简单的方法。

DESCRIPTION (provided by applicant): Ceramics are an ideal candidate for replacing metal-based restorative materials. Ceramics provide excellent chemical durability, wear resistance, biocompatibility, environmental friendliness, and esthetics. Nevertheless, widespread all-ceramic restoration use has been hindered by concerns related to marginal fracture resistance and clinical longevity. The overall goal of this ongoing research is to develop a practical method to produce tougher, more fatigue-resistant all-ceramic Dental restorations by modification with sputter-deposited thin-film surface coatings. Research conducted within the funded 6-year NIH project (once renewed) has focused on microstructural control of deposited films, assessing film effects on mechanical behavior of modified ceramic substrates, and characterization of film/environment interactions which affect film stress and substrate behavior. In the initial 3-year period yttria-stabilized zirconia (YSZ) was identified as the best thin-film ceramic coating material for the proposed application. It was demonstrated that YSZ thin-films produce no deleterious effect on bonding to a modified Dental ceramic surface, or on the esthetics of a translucent ceramic. In the second 3-year period, a unique interaction between deposited YSZ thin-films and environmental moisture was identified and characterized. TEM analyses of these films produced evidence of well defined and controllable tetragonal monoclinic phase transitions adjacent to internal defects. These can be manipulated to tailor film stress. Initial study of ductile/brittle polymer/YSZ laminate thin-films demonstrated promise for enhancement of fracture resistance of a brittle Dental substrate with control of the YSZ/water vapor interaction mechanism. Modeling of these structures indicates that specific thin-film structures can be created to provide optimal benefit in different environments. The proposed Specific Aims of this continued research are to: 1) Test the hypothesis that finite element analysis (FEA) of evolving YSZ thin-films, incorporating structural and stress state information, can predict the concentration/distribution of nano- and micro-dimensional defects, 2) Test the hypothesis that thin-film laminates with alternating ductile/brittle, low/high modulus (parylene/YSZ) layers will allow fine control of thin-film and film/substrate interfacial stress, allowing the direction (tensile, compressive, or zero) and magnitude of these stresses, and the interaction of the thin-film with the local environment to be controlled reproducibly, 3) Test the hypothesis that thin-film laminates with alternating ductile/brittle, low/high modulus layers will significantly enhance durability of traditional commercially available Dental ceramics, and 4) Demonstrate a viable technology for practical lab processing of varying permutations of YSZ and parylene/YSZ thin-films (development of a practical bench-top prototype deposition system). It is believed that this research will have a direct, positive impact on existing Dental ceramic technologies, enhancing the range of potential applications for low strength materials such as porcelain, and improving long term clinical efficacy. Development of non-metallic (e.g., amalgam-substitute) restorative materials is a high research priority due to biocompatibility issues and environmental concerns associated with metals waste and disposal. Ceramics offer the best combination of biocompatibility and environmental friendliness, but they have traditionally suffered from poor long-term clinical performance. The technology being investigated in this study has the potential to significantly improve the efficacy of existing Dental ceramics is a relatively simple manner.